1. Technical Field
The present invention relates to an optical device and a fabrication method thereof, and more particularly to a nano/micro-patterned optical device and fabrication method thereof.
2. Related Art
In recent years, the fabrication of micro fibers has been developed and reported by many research teams, and various optical devices have been fabricated using such micro fibers. For example, in U.S. Pat. No. 7,421,173, sub-wavelength diameter silica wires for low-loss optical wave guiding are provided, in which Mazur et al. take a tapered sapphire rod as a uniform heating medium to be heated in a flame, such that the fiber is drawn out to generate nanometer-sized diameter silica fibers. In U.S. Pat. No. 6,658,183, a process for fabricating tapered micro structured fiber system and a resultant system are provided, in which Chandaoia et al. heat a photonic crystal fiber with a flame, and respectively stretch two ends thereof in opposite directions, so as to generate thin wires with a diameter of 10 micrometers (μm) in a manner similar to fabricating a coupler. Accordingly, the optical device fabricated by using the nano/micro-level fibers includes an annular resonant cavity, an annular laser, a sensor, a filter, and other types of optical devices. Until now, many relevant documents have been published and issued, for example, M. Sumetsky, “Basic Elements for Microfiber Photonics: Nano/microfibers and Microfiber Coil Resonators”, Journal of Lightwave Technology, Vol. 26, Issue 1, pp. 21-27, 2008; or F. Xu et al., “Demonstration of a Refractometric Sensor Based on Optical Microfiber Coil Resonator”, Applied Physics Letters 2008, Vol. 92, pp. 101126. However, a common point of the above researches is that the nano/micro-level thin wire is not correctly placed according to the design, such that the nano/micro-level thin wire cannot be applied to the devices requiring precise designs, for example, a 1550/980 nm wavelength division multiplexer.
Furthermore, a V-shaped depressed groove for placing a fiber in the prior art has a V-shaped cross section. For example, in U.S. Pat. No. 6,621,951, thin film structures in devices with a fiber on a substrate are provided, in which Zhao et al. form V grooves on a substrate, and deposit thin films made of different materials, the thin films are used to enhance the adhesion between the fibers and the grooves. In addition, in US Patent Application No. 2007/0289698, fiber pattern applicator systems and methods are provided, in which Fleischman et al. use a fiber writer device, which includes an elongated tube with a proximal end and a distal end. The proximal end is connected to a fiber spool, so as to feed the fiber material continuously, and the distal end points to the position for placing the fiber. In addition, the fiber to be placed is placed in a channel of the elongated tube.
In the above two US patents (U.S. Pat. No. 6,621,951 and US 2007/0289698), the straight-linear fibers and any fiber with varied configuration can be placed, but it is quite difficult to apply the above two US patents to the nano/micro-level fibers. When the diameter of the fiber is as small as several micrometers or hundreds of nanometers, the fiber is not visible by human eyes, so that it is difficult to manipulate the fiber and place the fiber in the groove with human hands. Furthermore, the nano/micro-level fiber is easily adhered to any surface, such that it is difficult to place the fiber while maintaining a straight line shape of the fiber, and in this case, the V-shaped depressed groove cannot be used for wiring. In addition, the weight of the nano/micro-level fiber is extremely small, and if the fiber is not adhered to a surface of the substrate, the nano/micro-level fiber possibly moves or is even blown away by air movements.
In view of the above, it is a key aim in this industry to develop a patterned optical device based on nano/micro wires and a fabrication method thereof.